Adjustable thread ring gauge



April 1, 1952 G. HOHWART ET AL ADJUSTABLE THREAD RING GAUGE Filed March 11, 1946 i \gg INVEN 660/ e holrwd Efrain EMS,

Patented Apr. 1, 1952 ADJUSTABLE THREAD RING GAUGE George Hohwart and Ernest F. Hohwart, Detroit, Mich, assignors to N. A. Woodworth Company, Ferndale, Mich., a corporation of Michigan Application March 11, 1946, Serial No. 653,571

19 Claims. 1

This invention relates broadly to new and useful improvements in radially adjustable devices such as ring gages and journal bearings. More particularly the invention relates to a device of this type that will maintain substantially exact circularity throughout a range of adjustment; and, as a special application of the broad inventive concept, to an adjustable thread ring gage which is equipped with means for automatically compensating offset of the internal thread portions at opposite sides of the adjusting slot due to radial adjustment of the gage body.

As is well known to those skilled in the art, it is exceedingly difficult to radially adjust relatively rigid, one-piece metallic members such as journal bearings or ring gages which have circular supporting or engaging bores and at the same time maintain true circularity of the bores. In the case of bearings which support rotating parts, it is necessary to make such an adjustment from time to time to compensate for wear; and, in the case of ring gages, such adjustment must be made initially to assure a proper fit with the work and from time to time thereafter to compensate for wear. The problem is further complicated in both instances by the fact that an exceedingly fine tolerance must be maintained between the bore and the part adapted to fit therein.

Ring gages of the adjustable type have been generally unsatisfactory, because even though the gaging bore is absolutely circular when it leaves the manufacturer, it has heretofore been impossible to keep them reasonably round through even a slight adjustment. As a result, plain ring gages are usually made from a single, solid piece of metal and are not adjustable. This construction is feasible for plain ring gages, since they can be made cheaply and either replaced or reworked when they become worn. However, considerable time is required for reworking, and, in the case of large scale operations, the replacement costs are substantial. Consequently, even in the case of plain ring gages, the one-piece construction has not proved to be entirely satisfactory.

The one-piece, nonadjustable construction is seldom used for thread ring gages because, when so constructed they have a comparatively short life and the cost in making them to a fixed size is excessive. Instead, the so-called adjustable thread ring gage (AGD design) has been in use for a long time and universally accepted in spite of the fact that it has several generally recognized faults. As suggested above, one fault is that the gaging bore gets out of round when the gage is adjusted. Out of roundness is inherent in the standard gage construction and is due to the fact that the lap used to finish the gage body has a different pitch diameter than the gage when it is finally adjusted. Even though the gage is lapped round and to size, the first slight adjustment changes the circular bore into a shape approaching a triangle. This condition obviously affects adversely the accuracy and usefulness of the gage, but it is tolerated for want of something better.

Another fault of the standard AGD ring gage resides in the adjusting look. This lock comprises a sleeve which should fit snugly like a dowel pin in the free ends of the ring gage to hold the ends in one plane. However, if the sleeve has a dowel pin fit in the body, the latter cannot be adjusted without bending the sleeve. The standard practice has been to make the sleeve fit loosely, so that the body can be adjusted, and, when this is done, the ends move out of alignment or go out of plane when even a light blow is struck on the side of the gage body or when inherent stresses in the body are released. This going out of plane of course produces a change in the gage adjustment, so that the set plug no longer fits in the gaging bore. It is necessary to set and reset these gages almost daily, and the attendant loss of time and manpower are considerable.

In addition to the above, conventional thread ring gages of the adjustable type are faulty, in that the thread portions at opposite sides of the adjusting slot normally align properly in only one adjusted position of the gage body. When the body is adjusted either to a smaller or to a larger size, an axial step or offset is created between the corresponding thread portions due' to the thread angle. For example, if a l6 thread ring gage is adjusted .005" on the pitch diameter, a .0009" offset of the thread portions is created along the helix at the adjusting slot. This condition introduces an error on the pitch diameter of approximately .002". While these dimensions are small, they are significant, and an offset of the above amount is suflicient to render the gage faulty in operation. As a result of the offset, the internal threads of the ring gage do not properly fit the external threads being tested. Moreover, excessive wear occurs at the portions of the threads adjacent to the locking slot, and the initial adjustment of the gage changes as wear progresses. Thus,the gage does not retain its initial correct adjustment, and the an adjustable ring gage in which the ends are 7 held rigidly in alignment and prevented from going out of plane under normal treatment and abuse. V 7

Still another object of the invention is to provide a thread ring gage of the above type inwhich the gage body is held solidly in the selected adjusted position.

Yet another object of the present invention, is to provide a thread ring gage of the adjustable type in which offset of the thread portions at opposite sides of the-adjusting slot is automatir cally compensated when the gage body is locked in the adjusted position.

A further "object 'oi the invention is to provide a thread ring gage that is exceedingly strong and durable in construction but inexpensive to man- 'ufacture.

-fOther objects and advantages of the invention will be apparent during the course of the following description.

7 In 'the drawing forming a part of this specification and wherein like numerals are employed to designate like parts throughout the same,

operation of the adjusting and compenstaing means; and

Fig. '6 is an enlarged, fragmentary sectional view similar to Fig. 3 but showing a modified ad- :ju'sting and compensating m'ea'ns.

Considered "in "certain of its broader aspects the invention comprises-the provision of a cylindrical insert or bushing in a surrounding annular body member. This insert contains a bore and is supported. and retained by the body. According to ltheipre'sent invention the bore is positioned ec- V .c'entiically in theinsert, and the latter is mounted eccentrically in the body. The insert and "body areiprovided with radial adjusting and clamping slots respectively, which slots extend through. the thinnest portions of the members and are'disposed in diametrically opposed relation; win, the bore of the insert and the body opening which accommodates the insert are spaced apart and lie on a line joining the two slots. Thus the thinnest part of the insert faces the thickest part of the body and vice versa.

Y Suitable adjusting means is provided for tighteni-ng the body against the insert to contract the latter and for expanding the insert against the body. If necessary or desirable, either the insert or the body or both can'be formed with a plurality of adjusting slots to increase their flexibility. Byreason of theeccentric disposition of the bore and the body opening, itis possible to adjust the 7 insert over its entire range of adjustment withi the partsare'oombine'dand correlated, the insert is held solidly in the selected adjusted position. This is a marked and unexpected improvement over the conventional gages hereinabove referred to.

Manifestly this construction can be adapted to any device having an adjustable bore and where true circularity of the bore in all adjusted positions is essential. Bearings, plain ring gages, and thread ring gages are typical examples of such devices. a

More particularly, the adjusting means comprises a clamping screw carried by and extending across the clamping slot of the body and an adjusting screw which extends radially through the body and engages the ends of the insert at opposite sides of the adjusting slot. Each wall of the adjusting slot is shaped to provide angularly related bearing surfaces which seat solidly against the adjusting screw at opposite sides of a plane which extends through the axis of the screw and is disposed at right angles to the axis of the gage.

lhus the bearing surfaces collectively lock the ends of the insert and prevent them [from going out of plane. This slot construction is an independent feature of the invention; and, if de sired, it can be employed separately from eccentrio mounting hereinabove referred to. However, for obvious reasons, it preferably is used in conjunction with the eccentric mounting.

Preferably the walls of the adjusting slot are shaped to form a pyramidical seat for the adjusting screw, so that the ends of the insert are solidly held in the desired position. When this feature is adapted to plain ring gages the diagonal axis of the pyramidical seat is disposed parallel to a transverse plane through the insert, so that the ends of the latter are held in perfect alignment. However, if.the feature is adapted for thread ring gages, the diagonal axis of the pyramidical seat is disposed parallel to'the helix angle of the thread in the insert, so that when the gage is adjusted, the free ends of the-insert shift sideways to compensate for the helix angle of the thread, and the threadelernents are held rigidly in line with each other. r

The concept of providing a pyramidical'seat tion of the helix angle constitutes still another feature or the invention. In effect it is a special application of the second feature referred to above but should be considered separately, since it is capable of achieving results which the second feature, considered broadly, cannot achieve; viz., the elimination'of step or offset in-the hread portions at opposite sides of the adjusting slot when the gage is expanded or contracted.

As suggested, the seat is positioned so that the opposite bearing surfaces thereof engage the adjustingserew at diametrically opposite sides of the latter. When the internal threads' of the insert align normally, all of the bearingsur-faces engage the screw simultaneously so that pressure of the screw meansagainst'the surfaces merely expands the insert and holds it solidly in the selected adjusted position. However, if the thread portions atopposite sides'of the adjusting slot are out of alignment due to expansion or contraction of the'gage, certainof the bearing surfaces'only engage the screw,'and these surfaces are so positioned with ,respectto the latter that pressure exerted against the surfaces moves the ends of the insert axially in directions to compensate for such misalignment When'the ends of the insert are moved suificientl'y to bring the thread portions again into alignment, all

the bearing surfaces once more engage the screw which then functions not only to hold the ends of the insert properly spaced, but also to hold the internal threads properly aligned.

In its preferred form the adjusting screw merely comprises a hexagonal head, socket-typescrew which is screw-threadedly carried by the body in such manner that it is movable radially into and out of the adjusting slot in the insert. The screw has a spherical dog point nose which engages the coined pyramidical seat, and the bearing surfaces of the seat are inwardly tapered and collectively define four sides of a pyramidical figure. The surfaces or extensions of these surfaces at each side of the adjusting slot intersect at a point, which points are disposed on opposite sides of a plane through the axis of the screw and at right angles to the axis of the gage, and the angle which a line through these points of intersection makes with the diametric plane is a function of the thread angle. Thus, in any adjusted position of the gage body, the bearing surfaces are so positioned with respect to the adjusting screw that tightening the latter against the surfaces automatically compensates for misalignment of the internal gage threads.

If desired, the bearing surfaces may define a pyramidical figure having more than'four sides. but the latter is simpler and easier to form and as eflicient in operation as one having a greater number of sides. Moreover, the bearing surfaces may be either planar or curved. Planar surfaces establish a point of contact with the adjusting screw, and the curved surfaces change the point contact to a contact approaching an area. Thus, the planar surfaces offer less resistance to movement of the adjusting screw, but the curved surfaces provide a larger bearing surface and minimize any tendency of the screw to penetrate or Brinell these surfaces.

When the bearing surfaces are tapered, the adjusting screw engages therewith at substantially the middle of the insert, so that pressure is distributed substantially uniformly through the latter. As suggested, it is preferred that the nose of the adjusting screw be spherically curved so that it has a point contact with each of the bearing surfaces and friction between the two surfaces is reduced to a minimum.

The device will also function satisfactorily if the bearing surfaces are not tapered but extend parallel to the axis of the adjusting screw. However, in this case the screw engages the edge of the bearing surfaces at the anterior or proximate side of the insert, and the pressure is not distributed as uniformly through the latter as when the bearing surfaces are tapered. If nontapered bearing surfaces are employed, it is, of course essential that the nose of the adjusting screw be either tapered or spherically curved.

In the detailed description which follows, the invention is shown and described as applied to a thread ring gage; however, as hereinabove pointed out, the inventive concept is not limited to this construction but can be adapted for other purposes. 7

The insert is designated by the numeral I and the body by the numeral I2. Both the insert and the body are generally circular in shape, as shown in Fig. 1, and are relatively thick, as shown in Fig. 2. The insert I0 maybe made of hardened steel; The body I2 preferably is made of aluminum. When thus constructed, the gage is lighter in weight-than the standard AGD gage.

This is important in a device of this character, since the reduced weight results in less fatigue and assures a more sensitive feel.

As best shown in Fig. 1, the insert II] has a generally cylindrical peripheral surface and is provided with an eccentrically positioned, internally screw-threaded opening I4 which is. adapted to receive and snugly fit an externally screw threaded workpiece. In accordance with practices well known in the art, the opening I4 may be provided with threads of any suitable type or size, depending on the character of the particular work to be tested. At its thinnest portion the insert I0 is provided with a radial through slot I6 which permits radial expansion and contraction of the same, and the slot is adapted to receive an adjusting screw for holding the ends of the insert rigidly spaced apart. By reason of the fact that the instant construction maintains substantially true circularity of the gaging bore I4'in all adjusted positions of the gage the threads can be chrome-flashed for longer wear. This is an important consequence, since the increased wearability means less frequent adjustment and a saving in expense and labor. All attempts to chrome-flash the threads in AGD thread ring gages have been unsuccessful due to the triangular shape which these gages assume when they are adjusted.

The body I 2 also has a generally cylindrical peripheral surface and is provided with an eccentrically positioned opening I8 which receives and snugly fits the cylindrical periphery of the insert I0. It will be observed that the centers of openings I4 and I8 are spaced apart and that they lie on a line joining the slots I6 and 20, and, as suggested, this relationship is important in maintaining a high degree of circularity of the opening I4 throughout the range of adjustment. At the thinnest portion of the body I2 is a radial through slot 29 which permits radial expansion and contraction of the same. Since the body I2 is relatively thick and rigid it also is preferably provided with a plurality of substantially equispaced slots 22 which greatly increase its flexibility. All of the slots 22 extend radially outwardly from Opening I8, and all except the two slots nearest the adjusting slot 20 are provided with the usual terminal holes 24 which preferably increase progressively in size from the slot 20 to compensate for the increasing thickness of the body and to assure more nearly uniform contraction and expansion of the same. The body I2 is suitably colored to distinguish the go from the no go gage. According to the present invention, this is done by anodizing the body by processes well known to the art, green being used to designate the go gage and red to designate the no go gage. This practice adds color and beauty to the product and helps the operator to quickly identify the gages.

Adjustment of the body I2 is effected by a clamp screw 26 which is disposed in aligning openings 28 and 3E) and extends transversely across the slot 20. In order that no parts project from the body I2 and to provide a radial shoulder for the screw head, the latter is recessed in a countersink 32 at the outer end of opening 28. Opening 30 is internally screw-threaded to engage the external threads of screw 26 so that tightening of the screw radially contracts the body I2 and insert I0.

In practice the opening I4 is made approximately thesame. size as that-work to be tested. If it is desired to use the gage for testing slightly a 7 larger workpieces, the insert I is expanded, and, if it is desiredto use the gage for testing slightly smaller workpieces or if the opening l4 becomes Worn so that it no longer receives the workpiece with requisite snugness, the insert is contracted. In the case of thread ring gages,

however, such adjustment causes misalignment .ing opening 36 provided in the body I2. As 'best shown in Figs. .1 and 3, the opening 36 is "positioned in alignment with adjusting slot l6,..-and the screw 34 is provided :at its inner end with a longitudinal extension or nose 33 which .projects into confronting recesses or sockets 40 and 42 provided centrally in opposite walls of the slot. :Recesses 40 and 42 are inwardly tapered, as shown in Fig. 3, and the extension 38 has a spherically curved surface 39 which constitutes apressure element adapted to press against the walls of the recesses at substantially the middle of insert 10. Of course the precise point at which extension 38 engages the walls varies according to the selected adjusted position of the insert; however, since the gage has only a very small range of adjustment (.005" in the case of acne-inch gage) the extension is accommodated within therecesses in every adjusted position of the body.

In the embodiment of the invention hereshown byway of example, the recesses 40 and 42 are provided with fiat surfaces 44, 46 and 48; 50 respectively. These surfaces extend the full length or depth of the recesses .and of course are disposed at the same taper angle .as the curved portions'of the recess walls. observed that the flat surfaces of each recess are 'angularly related and that rearward or inner projections of these surfaces intersect on a line 52 which is disposed at an angle with respect to a diametric plane 54 which is transverse and normal to the axis of the gaging bore I4 at the axis of screw 34. The angle between the lines 52 and 54 is the same as the thread anglefand the relationship is such that pressure of screw 34 against surfaces 44, 45, 48 and 501moves the ends of insert it axially in opposite directions a distance sufficient to compensate for ofiset of the threads caused by adjustment of the gage. 7 It is believed that the above operation will be clarified by reference to Fig. 5 which shows diagrammatically the relative positions of the adjusting screw 38 and bearing surfaces 44, 46, 43 and 50 in two adjusted positions of the gage. In this view the thread portions'at opposite sides of the locking slot 15 are designated by the lines .55 and 58 which are'shown at an exaggeratedangle for clearness of illustration. It will be observed that line 52 is parallel with the thread portions 56 and 53. Thus the angle between line 52 and the diametric plane 54 is equal to the thread angle.

Thefour bearing surfaces '44, 45, 43 and 5B are so "disposed with respect to the nose 38 of lusting screw 34 that the thread portions 55 and 58 align when the nose simultaneously. engages the bearing surfaces without moving the ends eflinsert l0 axially,- as,shown by the full lines in Fig. .5. However, if the adjusting screw 234. is

It will be backed away and the insert I0 is contracted by the body l2, the'parts assume positions substantially as shown by the dotted lines in Fig. 5,. It will be observed that in this position of theinsert ID, the thread portions 56 and 58 are offset, and that, due to the manner in which the bearing surfaces 44, 46, 48 and 50 are positioned angularly with respect to the plane 52, the former are no longer disposed symmetricallyabout the nose 38. During contraction of the insert 10, bearing surfaces 46 and 48 move closer together than bearing surfaces 44 and 50. Consequently when the screw 34 is advanced to lock the body in its adjusted position, the-nose 38 .first engages bearing surfaces 46 and 48. By reason of the inclined position of these surfaces, pressure exerted by the nose 33 moves the ends of insert 10 axially in opposite directions, as indicated by the arrows, and flexing of the insertin this manner moves the thread portions 56 and 58 again into proper alignment. Adjusting screw 34 is tightened until the nose 38 again simultaneously engages all iour of the bearingtsurfacesto hold the insert solidly in the radially and axially adjusted position. The body remains so positioned until adjusting screw 34 is retracted, at which time the inherent resiliency-of the insert returns it :to the initial radial position and permits the ends of the body to move again into alignment.

It will be readily appreciated that 'asimilar operation occurs when the gageis expanded.

Attention is now directed to Fig. 6 which shows a modified adjusting and compensating'means. In this form-of the invention the integral nose 38 is replaced by a sphere or .ball 60 which fits in recesses 40 and 42 and is independent of andactuated by the end of adjusting screw 34. By reason of its spherical surface, the ball-60 has a point contact with each of the four bearing surfaces 44, 45, 48 and 50 in all adjusted positions of the gage, thus assuring minimum resistance to adjustment of the insert to. I

The form of the invention shown in Fig. 6

operates in the same manner to achieve the 26 is tightened to contract the gage body 12 against the insert 10 and the insert 10 against the adjusting screw. .It .will be appreciated that in tightening the clamp .screw '25,, it serves :to contract the body 12 which acts in the manner of a hose clamp to apply a radially .contractive' force uniformly against the insert [0. Alternatively, the screws '26and '34 may be loosened, the

set plug inserted'in the opening l' land'thescrew 26 tightened'to contract'the body l2 .on the insert 1D and the insert '10 'onthe set plug. Tightening is continued until the master iset .plug is locked "against rotation, and the adjusting-screw 34 is then tightened-againstthe bearing surfaces 44, 46, 48 and 50 to expand insert I0 against the wall of opening 18 whereby to'relieve the master plug sufficiently so that it can be rotated in the body with precisely the desired amount of re sistance. By this procedure it is possible to ob-' tain a very fine radial adjustment of the gage body. The adjusting screw 34 holds the insert to rigidly in the selected and adjusted position and, in the case .of thread :ring gages, also mom-- pensates automatically for offset of the threads due to such adjustment.

It is to be understood that the forms of the invention herewith shown and described are to be taken as preferred examples of the same and that various changes in the size, shape, and arrangement of parts may be resorted to without departing from the spirit of the invention or the scope of the appended claims.

Having thus described the invention, we claim:

1. A device of the character described comprising an inner radially adjustable member having a generally cylindrical peripheral surface, an eccentrically positioned opening therein, and a radial through slot at substantially the thinnest portion thereof; and an outer adjusting member having an eccentrically positioned opening which snugly fits the periphery of said inner member and a radial through slot at the thinnest portion thereof, the centers of said eccentric openings being spaced apart and disposed on a line joining said through slots.

2. -A device of the character described comprising an inner radially adjustable substantially disk-shaped insert member having an eccentrically positioned opening therein and a radial through slot at substantially the thinnest portion thereof; and an outer substantially disk-shaped body member having an eccentrically positioned opening therein which snugly fits the periphery of said insert member and a radial through slot at substantially the thinnest portion thereof, the centers of said eccentric openings being spaced apart and disposed on a line joining said through slots.

3. A device of the character described comprising an inner radially adjustable substantially disk-shaped member having an eccentrically positioned opening therein and a radial through slot at the thinnest portion thereof; and an outer substantially disk-shaped adjusting member having an eccentrically positioned opening therein which snugly fits the periphery of said inner member and a radial through slot at the thinnest portion thereof, the centers of said eccentric openings being spaced apart and disposed on a line joining said through slots, said adjusting member having a plurality of circumferentially spaced radially extending slot means which open through its inner surface but terminate short of its peripheral surface and increase progressively in depth from the radial through slot.

4. A device of the character described comprising an inner radially adjustable substantially disk-shaped member having an eccentrically positioned opening therein and a radial through slot at the thinnest portion thereof; and an outer substantially disk-shaped adjusting member having an eccentrically positioned opening therein which snugly fits the periphery of said inner member and a radial through slot at the thinnest portion thereof, the centers of said eccentric openings being spaced apart and disposed on a line joining said through slots, said adjusting member having a plurality of circumferentially spaced radially extending slots which open through its inner surface but terminate short of its peripheral surface and are provided at their outer ends with terminal holes which increase progressively in diameter from the radial through slot. 7

5. A device of the character described comprising an inner radially adjustable member having a generally cylindrical peripheral surface, an eccentrically positioned opening and a radial through slot at substantially the thinnest portion thereof; an outer adjusting member having an eccentrically positioned opening which snugly fits the periphery of said inner member and a radial through slot at the thinnest portion thereof disposed substantially in diametrically opposed relation to said first-mentioned slot; and radially adjustable means carried by said outer member positioned to enter the radial through slot of said inner member and adapted to be engaged by the walls of said slot when the device is adjusted to size.

6. A ring gage comprising a substantially diskshaped inner member having an eccentrically positioned opening and a radial through slot at substantially the thinnest portion thereof; a substantially disk-shaped characteristically colored outer member having an eccentrically positioned opening which snugly fits the periphery of said inner member and a radial through slot at substantially the thinnest portion thereof disposed substantially in diametrically opposed relation to said first-mentioned slot, said outer member having a plurality of circumferentially spaced, radially extending slots which open through its inner surface but terminate short of its peripheral surface and increase progressively in depth from the radial through slot; means for contracting the outer member whereby to apply a radially contracting force against said inner member; and a radially adjustable member carried by the outer member positioned to engage the walls of the first-mentioned slot when the gage is adjusted to size.

'7. A ring gage comprising a substantially diskshaped body having an opening therein and a radial through slot; an insert fitting snugly in said body opening, said insert provided with a gaging bore and a radial through slot; means for contracting the body against said insert; and

a radially adjustable member carried by the body positioned to enter the slot in said insert, each wall of said slot having separate bearing surfaces positioned for engagement with said adjusting member on opposite sides of a diametric plane through the axis of the latter and at right angles to the axis of said body.

8. A ring gage comprising a substantially diskshaped body, having an opening therein and a radial through slot; an insert fitting snugly in said body provided with a gaging bore and 'a radial through slot; means for contracting the body against said insert; and a radially adjustable member carried by the body positioned to enter the slot in said insert, each wall of said slot ha'ving'separate angularly related, radially inwardly tapered bearing surfaces disposed to engage the adjusting member on opposite sides of a plane which extends through the axis of such member and is disposed normal to the axis of said body.

9. A thread ring gage comprising an internally threaded annular gaging member having spaced ends which define an adjusting slot; a body around said gaging member adapted to apply a radially contracting force against the same; and an adjusting member carried by the body adapted for movement axially into and out of the adjusting slot and. to press against the walls of the same, each of said walls having a socket and each of the sockets provided with a plurality of tapered bearing surfaces disposed to engage the adjusting member on opposite sides of a plane through the axis of such adjusting member and normal to the axis of said gaging member', said bearing surfaces arranged to simultaneously engage the adjusting member-and thetaper of such surfaces being such that their projected apexes coincide-when the gaging member is positioned so that its ends and the thread portions on opposite sides of the locking slots align, the arrangement being such that, after adju'stment of the gaging member from the above 7 position, pressed engagement between the adset'ofsaid internal screw threads due to such adjustment 7 r n 10. A'thread ringgage comprising an internally threaded annular gaging member having spaced ends which define an adjusting slot; a body around said gaging member adapted to 'apply'a radially contracting force against the same; and an adjusting member carried by said body adapted for movement axially relative to the walls of said adjusting slot, said walls being shaped to define a symmetrical geometric figure having at least two angularly related bearing surfaces on'each side of. the adjusting slot and said bearing surfaces so arranged with respect to the adjusting member that, when the thread portions on opposite sides of the adjusting slot align, the bearing surfaces engage the adjust ingmember simultaneously, but, when the gaging member is adjusted radially and said thread portions misalign, the'bearing surface engage the adjusting member only on opposite sides thereof and at opposite sides of a plane extending through the axis of the latter and disposed normal to the axis of said gaging member whereby the ends of said gaging member are moved axially in directions to compensate offset 'of said thread portions. 7

' IL A thread ring gage comprising an internally threaded annular gaging member having spaced ends which define an adjusting slot; a body around said gaging member adapted to apply a radially contracting force against the same and a radially adjustablemember carried by the body and movable axially relative to the Walls of said slot, each wall of the slot having a pair of fiat, tapered bearing surfaces and said surfaces collectively arranged to define four sides of a pyramidical figure when the thread portions on opposite sides of" the slot align, the sides of the pyramid beingangularly disposed with respect to a diametric plane through the axis of said adjusting member andnormal to the axis of said gaging member, and the angle of said sides with the plane" being: a function of the thread angle whereby pressed engagement between the adjusting member and the bearing surfaces moves the ends of the-gaging member axially in opposite directions to compensate axial offset of the thread which results when the gaging memher is adjusted.

12. A thread ring gage comprising an internally threaded annular gaging member provided with internal threads having a predetermined thread angle and spaced ends which define an adjusting slot'; a body around said gaging member adapted to apply a radially contracting force against the same; an adjusting member carried by said body positioned to engage the walls of said adjusting slot and actuator means for pressing the adjusting member against said walls, each wall of the slot having a pair of fiat, tapered bearing surfaces and said surfaces collectively arranged to define four sides of a pyramidical figure when the thread portions onv opposite sides of the slot align, the sides: of said pyramidical figure being angularly disposed with respect to a plane through the axis of said adjusting member and normal to the axis of said gaging member, and the angle of the sides with the plane being a function of the thread angle whereby engagement between the adjusting member and the bearing surfaces moves the ends of the gaging member axially in opposite directions to compensate axial offset of the threads which results when the gaging member is adjusted.

13. A thread ring gage comprising an inner member having a generally cylindrical peripheral surface, an eccentrically positioned screwthreaded opening and a radial through slot at substantially the thinnest portion thereof, said screw-threaded opening being chromium flashed; an outer member having an eccentrically positioned opening which snugly fits the periphery of said inner member and a radial through slot at substantially the thinnest portion thereof positioned substantially in diametrically opposed relation to said first slot; and means for contracting the outer member against said inner member.

14. In athread ring gage, a gaging element comprising an internally threaded annulus, said annulus provided with a radial through slot and each wall of said slot having a pair of flat, tapered bearing surfaces, said bearing surfaces collectively arranged to define four sides of a pyramidal figure when the thread portions on opposite sides of the slot align, the sides of the pyramid being angularly disposed with respect to a plane through the projected apex of said pyramidal figure'and normal to the axis of said gaging element and the angle of said sides with the plane being a function of the thread angle.

-15. In a thread ring gage, a gaging element comprising an internally threaded annulus, said annulus provided with a radial through slot and the'walls-of said slot having fiat tapered bearing surfaces, said bearing surfaces collectively arranged to define sides of a pyramidal figure when the thread portions on opposite sides of the slots align, the sides of the pyramid being angularly disposed with respect to a plane through a projected apex of the pyramidal figure and normal 'tothe axis of said gaging element, and the angle of said sides with the plane being a function of the thread angle. 16. A thread ring gage comprising an internally threaded annular gaging member, having spaced ends which define an adjusting slot, a body around saidgaging member adapted to apply a radially contracting force against the same, a pressure element carried by said body positioned to engage and adjustable radially relative to the ends of said gaging member, and cam surfaces on the ends of the gaging member engageable with said pressureelement upon contraction of said gaging member by said body to fiex said ends axially in opposite directions to compensate for axial offset produced in the threads as a result of such contraction. I

l7. A thread ring gage comprising an internally threaded annular gaging member having spaced ends which define an adjusting slot, a body around said gaging member adapted to apply a radially contracting force against the same" apressure element disposed between and engageable with the ends of said gaging member, means for moving the pressure element radially with respect to the gaging member, and cam surfaces on the ends of the gaging member engageable with said pressure element on opposite sides thereof and arranged to flex said ends axially in opposite directions upon contraction of said gaging member by said body whereby to compensate for axial offset produced in the threads as a result of such contraction.

18. A thread ring gage comprising an internally threaded annular gaging member having spaced ends which define an adjusting slot, a body around said gaging member adapted to apply a radially contracting force against the same, a pressure element disposed between and engageable with the ends of said gaging member, a screw extending radially into the body behind said pressure element co-operative with the latter to move the same radially to and from said gaging member, and cam surfaces on the ends of the gaging member engageable with said pressure element on opposite sides thereof and arranged to flex said ends axially in opposite directions upon contraction of said gaging member by said body whereby to compensate for axial oflfset produced in the threads as a result of such contraction.

19. A thread ring gage comprising an internally threaded annular gaging member having a radial through slot defining spaced ends and permitting contraction of said gaging member, a body around said gaging member adapted to apply a radially contracting force against the same, a pressure element carried by said body movable radially with respect to said gaging member and positioned to engage the spaced 35 Number ends of the gaging member, gain surfaces on the ends of the gaging member engageable with said pressure element upon contraction of said gaging member by said body to flex said ends axially in opposite directions to compensate for axial ofiset produced in the threads as a result of such contraction, and other cam surfaces on the ends of the gaging member engageable with said pressure element when the ends of the gaging member have been flexed sufficiently to exactly compensate for offset in the threads whereby to limit further fiexure of said ends and to co-operate with said first-mentioned cam surfaces and said pressure element to hold said ends positioned with the threads exactly in alignment.

GEORGE HOHWART. ERNEST F. HOHWART.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 664,995 Ernst Jan. 1, 1901 675,596 Green June 4, 1901 1,487,803 Peterson Mar, 25, 1924 1,913,674 Kaufman June 13, 1933 2000,7823 Muller May '7, 1935 2,353,626 Schnaars July 11, 1944 2,419,263 Hohwart Apr. 22, 1947 2,443,904 Fishman June 22, 1948 FOREIGN PATENTS Country Date 261,741 Germany June 28, 1913 

